Go to the Control-C User portal
https://backup.control-c.com/Account/Login
1. Click on Organisation Overview in the menu
2. Look for the Organisation Name that is disconnected and click on the name.
3. Click 'Enable Xero Integration' to be guided to the reconnection wizard.
NOTE: CANT SELECT THE XERO ORG?
If you are unable to select the Xero Org because it is greyed out, then you need to go to your Xero Settings page and delete the Control-C connection and then try reconnecting again. Detailed instructions can be found in this article here